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Date: Mon, 14 Dec 2015 12:44:21 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>,
        linux-kernel@vger.kernel.org, Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>
Subject: Re: [PATCH v3 14/17] perf: Remove subcmd dependencies on strbuf
Message-ID: <20151214154421.GO6843@kernel.org>
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Em Sun, Dec 13, 2015 at 10:18:14PM -0600, Josh Poimboeuf escreveu:
> Introduce and use new astrcat() and astrcatf() functions which replace
> the strbuf functionality for subcmd.

<SNIP>
 
> diff --git a/tools/perf/util/subcmd-util.h b/tools/perf/util/subcmd-util.h
> new file mode 100644
> index 0000000..98fb9f9
> --- /dev/null
> +++ b/tools/perf/util/subcmd-util.h
> @@ -0,0 +1,24 @@
> +#ifndef __PERF_SUBCMD_UTIL_H
> +#define __PERF_SUBCMD_UTIL_H
> +
> +#include <stdio.h>
> +
> +#define astrcatf(out, fmt, ...)						\
> +({									\
> +	char *tmp = *(out);						\
> +	if (asprintf((out), "%s" fmt, tmp ?: "", ## __VA_ARGS__) == -1)	\
> +		die("asprintf failed");					\
> +	free(tmp);							\
> +})

Hey, don't add die() calls, please.

> +
> +static inline void astrcat(char **out, const char *add)
> +{
> +	char *tmp = *out;
> +
> +	if (asprintf(out, "%s%s", tmp ?: "", add) == -1)
> +		die("asprintf failed");
> +
> +	free(tmp);

Ditto.

And I think that this should go into tools/include/string.h and
tools/lib/string.c, no?

We should try to look at the kernel and try to follow naming, semantics,
etc as much as possible. The kernel doesn't have a astrcat, just
kasprintf() (that is in linux/kernel.h, perhaps because in userland
asprintf is in stdio.h, not in string.h) , wonder how something like
astrcat is done there... Doing some research now.

- Arnaldo

> +}
> +
> +#endif /* __PERF_SUBCMD_UTIL_H */
> -- 
> 2.4.3